import java.util.Scanner;

public class Success {
    public static void main(String[] args) {
        double sco = 0;
        Scanner scanner = new Scanner(System.in);
        System.out.println("请输入分数为多少：>");
        sco = scanner.nextDouble();
        if (sco < 60) {
            System.out.println("Failed");
        } else if (sco >= 60 && sco <= 70) {
            System.out.println("D");
        } else if (sco >= 71 && sco <= 80) {
            System.out.println("C");
        } else if (sco >= 81 && sco <= 90) {
            System.out.println("B");
        } else if (sco >= 91 && sco <= 100) {
            System.out.println("A");
        }
    }

}
